This invention relates to relays for switching of ultra high frequency coaxial circuits, and is of the type comprising three fixed coaxial switching contacts including a centrally located contact, and two rigid blade contacts arranged to alternately engage the central contact and one of the other two coaxial contacts. The arrangement is such that when one of the rigid blade contacts is in a circuit closing position, the other contact engages a ground plane. The contact blades are fixed respectively to isolating pushers or drivers and each of the pushers is driven in a straight line by a leaf spring, in turn driven by a magnetic armature, having two arms and pivotal about a central axis, under the action of an electromagnetic motor. The relay can be of the change-over switch type.
The electromagnetic motor can, for example, be of the monostable type, advantageously having a winding whose magnetic core has its axis intersecting the pivotal axis of the armature, and a first pole in the form of a bar of magnetic material having a pole end facing one of the arms of the armature and its other end connected by a magnetic material connecting plate to the core. Advantageously, the magnetic circuit includes a permanent magnet between the other pole element and the magnetic connecting plate. The other pole element is in opposed relation to the other arm of the armature. The magnetic connecting plate provides for the passage of magnetic flux from the permanent magnet through the core of the winding and the bar forming the first pole piece and which is opposed to the first arm of the armature. The flux created by the permanent magnet in the core of the winding is of opposite polarity to the flux created in the core when the winding is energized.
To assure proper operation of such switching relays, it is necessary to obtain the highest quality of transmission possible between the lines of the switched coaxial line, and very high isolation between the lines of the non-switched coaxial line.
For this result one has previously used return springs which oppose the force with which the pushers are driven by the armature, and which press the blades of the contacts connected to the pushers against the ground plane.
Relays for ultra high frequency coaxial switching, of the type mentioned, have the disadvantage that high energy is required to assure sufficient force to press the contact for the switched line into good engagement with the coaxial contacts of the switched line, to obtain good transmission, and to also obtain sufficient force to press the contact associated with the unswitched line against the ground plane to assure good isolation. The bearing pressure with the ground contact plane depends upon the return force of the springs which support the pushers, and this return force is opposed to and must be overcome by the pusher when it is driven by the action of the relay motor.